FFMI Calculator gives an estimation of the body Fat-Free Mass Index (FFMI) value based on the human height, weight and body fat percentage. To calculate the body FFMI, choose appropriate measurement units and specify the height, weight and body fat percentage either using the sliders or inserting the data in the calculator fields.
What is FFMI
Fat-Free Mass Index, abbreviated by FFMI, is a numeric parameter that indicates a person’s muscle development. It can be used to estimate lean muscle mass and track the success of strength training, or to evaluate the effectiveness of a diet.
FFMI is often used as a replacement for body mass index (BMI), which is not suitable, in particular, for muscular people. Athletes, for example, have higher muscle mass and can be placed inappropriately in an overweight or obese category based on BMI value alone.
BMI is intended mostly for untrained people and gives only an initial assessment of the state of their body. Fat-free mass index, on the contrast, is more suitable for sports people and professional athletes and gives them a much more accurate assessment of their physical condition.
A higher FFMI value indicates more muscle and, respectively, less fat in relation to height. Since FFMI also takes into account the percentage of body fat, it is much more accurate in assessing a person’s physical condition compared to BMI,
Fat Free Mass Index Formula
To calculate FFMI, you must know your height, weight, and body fat percentage. The percentage of your body fat can be measured in a clinical setting using a scan machine or bioelectrical impedance scale. The body fat percentage for adults can also be estimated using gender-based formulas in conjunction with BMI. The simplest option is just using our Body Fat Calculator.
Knowing the above parameters, further calculations are performed according to the following formulas which we use in our FFMI calculator:
Body Fat = Weight (kg) × Body Fat (%) / 100
Fat-Free Mass = Weight (kg) – Body Fat (kg)
FFMI = Fat-Free Mass (kg) / (Height (m))2
Normalized FFMI = FFMI + 6.1 × (1.8 – Height (m))
As you can see, first we calculate the body fat mass and fat-free mass, then we calculate the FFMI and the normalized, or adjusted, FFMI. The normalized FFMI is used for persons that are taller than the average height.
It is important to note that both the body fat mass and fat-free mass are measured in the same units as the weight. But in the formula for FFMI we must take the fat-free mass in kilograms and the height in meters. Therefore, the FFMI has units of kg/m2, but in practice the units are not specified. Similarly, in the formula for normalized FFMI the height must be in meters, but the units for this parameter are not indicated as well.
As it is easy to see, the fat-free mass index is calculated using the same formula as the body mass index (BMI), but instead of body weight, fat-free mass is taken.
In what follows is the table showing range of FFMI score classifications.
It was statistically established that for men the average FFMI is 18-20, and for women the average FFMI is 14-17. However, athletes may have higher results, and skinnier people may have lower results, while staying healthy.
While in some cases scores of 26 to 28 can be achieved naturally, this result usually indicates the probable use of steroids. But FFMI values above 28 are hardly achievable naturally without the use of steroids.
Related calculators
Check out our other health calculators such as BMI Calculator or Lean Body Mass Calculator.
Disclaimer. Please remember that this calculator is only one of many ways to assess your fat and muscle mass. In case of any concerns about your health or physical fitness, please consult your physician to address your specific situation.